Machine for making spiral coverings or sheaths on filiform materials



Dec. 2,' 1941. v. A. FOLCO 2,264,437, MACHINE FOR MAKING SPIR AL COVERINGS 0R SHEATHS ON FILIFORM MATERIALS Filed Sept. 27, 1940 Patented Dec. 2, 1941 MACHINE FOR MAKING SPIRAL COVERINGS OR SHEATHS ON FILIFORM MATERIALS Vincenzo Angelo Folco, Turin, Italy, assignor to Societa Anonima Elettrovetro Nazionale, Milan, Italy, a corporation of Italy Applicationseptember 27, 1940, Serial No. In Italy September 30, 1939 8 Claims. (Cl. 51- 18) This invention relates to machines intended to provide spiral sheaths or coverings on filiform materials as wires, cables, electric conductors and the like, of the class in which the thread intended to build up said covering is arranged in a bobbin on an annular winding head rotated at a constant speed by driving means, said thread being thus laid and wound on said filiform ma-- terial which in turn is fed longitudinally through said rotating annular winding head, with a speed which is in a predetermined ratio with respect to the angular speed of said rotating head.

In machines of the class above referred to, the thread bobbin is located on the winding head by means of a bobbin carrier which comprises a On the other hand the frictional engagement of the head 'and carrier, depends'upon the weight of the bobbin carrier and bobbin since this weight forces the bobbin-carrier disk into engagement with the winding head which drives it.

During operation the weight of the bobbin decreases in proportion with the amount of thread which leaves the bobbin' to be wound on the conductor 5, and this decrease is in proportion to the gradual decrease of the bobbin diameter I while the weight of the bobbin carrier itself remains unchanged. This produces a variation in disk resting on said head and frictionally engaged therewith. The rotarymotion of the head is imparted to the bobbin carrier and bobbin frictionally to permit a creeping motion of 'the bobbin carrier with respect to the head driving it. Due to the unwinding of the thread from the bobbin which is aflixed to the filiform material to be covered or sheathed, this creeping motion occurs with a speed which is substantially negligible with respect to the speed of the head and also with respect to the speed of the bobbin carrier and bobbin.

This invention has for its object automatic governing means for winding heads of the above stated class. In accordance with this invention the bobbin carrier is provided with wings or flaps which apply to said bobbin carrier 3, control action dueto the resistance created by their motion through the air, said control action improving the operation of the winding head and securing operative conditions which are particularly satisfactory.

On the annexed drawing:

Fig. 1 is a graph illustrating the operation of the winding heads to which this invention refers,

Fig. 2 is a central section of an embodiment of this invention,

Fig. 3 is a central section of a modified construction and Fig. 4 is a plan view thereof.

As shown in Figs. '1 and 2, in winding heads of the type indicated, the rotary drive is imparted by a rotary head i actuated by a hollow shaft 9, 9' frictionally to a carirer 2, 2. The thread bobbin 3, 4 is fixed on said carrier 2, 2 while a conductor 5 or the like to be covered is fed longitudinally through said hollow shaft 9, 9 and annular head I and carrier 2, 2' as shown by the arrow, by means not shown.

With the above construction, at the instant the drive and operation of the winding head i is stopped, the carrier 2, 2' with the bobbin'3, 4 thereon tends to rotate further. This is liable to cause the thread. which unwinds from the bobbin to become entangled or to break.

the tension operative on the thread which is a disadvantage.

In the apparatus of this invention in order to remove this disadvantage the wings I are fast on the carrier-2. The wings 1 due to the resistance created in their motion through the air, apply a damping or braking action to the bobbin carrier 2, 2 and tends to cause it to stop its motion as soon as the winding head I comes to'rest.

In a. preferred embodiment of this inventionthe wings I are shaped in a manner causing them to act to compensate for the weight of the bobbin carrier, thus causing the tension operative on the thread during its unwinding to depend on the weight and radius of the thread bobbin or package only, and preventing such tension from taking such values as would cause the thread to break.

In fact, during the operation the portion 4 of the thread ,which goes from the bobbin to the conductor 5, having one of its ends engaged with the conductor 5 and its other end connected with the thread wound on the bobbin at the point where the thread pays therefrom, is under a by the head I to the carrier disk 2, the tensionoperative on the thread 4 is equal to the torque due to said frictional action divided by the radius of the outer periphery of the bobbin.

Said frictional action torque is in turn proportional to the total weight which is the sum of the weight of the bobbin carrier and of the weight of the bobbin. The Weight of said carrier is a constant while the bobbin weight varies as the square of the bobbin radius, this radius varying during the unwinding of the thread from the bobbin.

Let M be the frictional action torque operative on the bobbin carrier, 1' the variable radius of the bobbin and F the tension operative on the thread, F is equal to M 1'; M in turn is the total of a constant term (it depending on the weight of the bobbin carrier and of a term varying as the square of the thread bobbin radius (Kvr that is M =Ii' -1-Ke1'. Consequently the tension F is equal to it consists of the sum of two terms f and ,1" which respectively equal to Kvr.

The operative conditions are clearly shown by the graph of Fig. i where along axes F and r are carried the values of the tension operative on the thread and of the bobbin radius during the thread unwinding. In said graph the first term of the tension FE in register with each value of the radius r is given by the ordinates of the equilateral hyperbole indicated by f and whose equation is: Fr=ffp while the second term is given by the registering ordinates of the straight line whose equation is: f'=.l'fvr.

he shown by the graph, during the decrease of the thread bobbin radius from its maximum value if: its minimum value n the total action F operative on the thread is shown. by the ordinates of the curve l? obtained by adding i and f to each other.

Said action varies from its value F2 to its value F1. It first decreases and subsequently it materially increases to such an extent as to cause the thread often to break.

By imparting to the wings 'l amxed on the bobbin carrier 2, 2 proper inclination with respect to the horwontal and in such a direction that they are opposed to the direction of rotation, there is obtained an upward action to the and mounted on a hollow shaft 9, 9 which is driven at constant rotary speed by driving means not shown.

The bobbin carrier includes a disk 2 which rests freely on the head i and a sleeve 2' fast with the disk 2 and having a tube 3 on which the thread bobbin l is wound, said bobbin being thus connected in rotation with the disk 2. The sleeve 2' of the carrier is inserted on the end portion 9' gen of the shaft 9 of the head and acts to center the bobbin carrier.

The filiform element 5 on which the thread i is wound spirally when unwound from the bobbin 3 and which in the described embodiment is an electric conductor to be covered by means of the thread 4, is fed longitudinally through the winding head i under the action of means, not shown, causing it to run with a constant speed having an invariable ratio with the conano e-av stantangular speed or the head i, and the thread t is directed towards the conductor 5 by means of a guide 6 located on the head i.

The disk 2 engages the head 1! under the gravity action which in turn depends on the weight of the bobbin carrier and on the weight or the bobbin and the drive of the bobbin carrier by the head occurs under the action of the friction between the dish 2 and the head i. Consequently when the head i is stopped the bobbin carrier 2, tends to maintain itself in motion due to the momentum of the bobbin carrier 2, 2 and of the bobbin 3, located thereon. This might break. the thread l or cause an exceedingly long length of thread to unwind from the bobbin which would become entangled in the machine and cause trouble.

As above suggested, to remove such objectionable conditions the bobbin carrier is provided with wings 5 fast thereon which develop a bralring effect on the bobbin carrier due to air resistance and the bobbin carrier stops at the time the head i stops its motion.

To increase the braking or damping action of the wings "l on the bobbin carrier the head i may be provided with flaps it parallel to the wings i of the bobbin carrier 2. The flaps ii direct air towards the wings l and improve the braking action of the wings lhe wings l or the flaps b or both may be located with their generatrix lines inclined with respect to the radial direction, to further improve the braking action.

By the described arrangement the braking action of the bobbin carrier does not depend upon the friction between the dish 52 and head i and consequently the coeflicient of friction between the disk. and the head may be reduced to a minimum without affecting the efficiency of braking action, with the advantage that the tens on on the thread is reduced further during the, winding operation as evidenced by the straight line I" in the graph of Fig. i.

In the embodiment of Figs. 3 and c the wings of the bobbin carrier impart to said carrier an upward thrust which compensates for the weight of the bobbin carrier and for the corresponding term in the friction torque driving the said carrier, and thus cause the tension operative on the thread ii to be independent of the term due to the weight of the bobbin carrier and to depend only on the term due to the bobbin weight (I' to f", Fig. 1).

In this construction the bobbin carrier, 2, 2' is made as described with respect to Fig. 2, while the wings l are inclined to provide an angle opening opposite to the direction of rotation, to receive on their bottom face the reaction of the air in which they move. The wings 1 thus receive an upward thrust and they impart it to the assembly of the bobbin carrier and bobbin. Said upward thrust being in opposition to the weight of the bobbin carrier tends to nullify the influence of said weight on the frictional engagement of the bobbin carrier with the driving head 8.

By giving .proper values to the inclination of the wings I, their total area and the distance from the rotary axis they are located and finally by taking in account the speed of operation of the head and bobbin carrier, the weight of the bobbin carrier 2, 2' may be fully compensated for.

In this case also, the wings i apply a braking action at the time the head i is stopped and said head may be provided with flaps 8 to improve said braking action as above described.

What I claim as my invention and desire to secure by United States Letters Patent is:

1. In a machine for aflixing a covering on a filiform element said covering consisting of a thread wound spirally. on said element, an annular rotary head, an annular carrier loosely rest-,

ing on said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longi= tudinally through said head, carrier and bobbin, and wings fast on said carrier said wings being inclined with respect to their path line and de veloping and applying to said carrier an upward thrust to compensate for the weight of said bobbin carrier as an efiect of their inclination and of the resistance exerted on said wingsby the medium through which they travel in the rotation of said carrier.

2. In a machine for affixing a covering on a filiform element said covering consisting of a thread wound spirally on said element, an. annular rotary head, an annular carrier loosely restingon said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longitudinally through said head, carrier and bobbin, wings fast on said carrier said wings developing and applying to said carrier a control action in respect of the rotary movement thereof as an eflect of the resistance exerted on said wings by the medium through which they travel in the rotation of said carrier and flaps on said head to direct said medium towards said carrier wings to assist their action.

3. In a machine for afiixing a covering on -a filiform element said covering consisting of a thread wound spirally on said element, an annular rotary head, an annular carrier loosely rest-' ing on said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longitudinally through said head, carrier and bobbin, wings fast on said carrier said wings being inclined with respect to their path line and developing and applying to said carrier an upward thrust to compensate for the weight of said bobbin carrier as an effect of their inclination and of the resistance exerted on said wings by the medium through which they travel in the rotation of said carrier, and flaps on said head to direct said medium towards said carrier wings to assist their action.

4. In a machine for afiixing a covering on a filiform element said covering consisting of a thread wound spirally on said element, an annular rotary head, an annular carrier loosely resting on said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longitudinally through said head, carrier and bobbin, wings fast on said carrier said wings being inclined with respect to their path line and developing and applying to said carrier an upward thrust to compensate for the weight of said bobbin carrier as an effect of their inclination and of the resistance exerted on said wings by the medium through which they travel in the rotation of said carrier, and flaps on said head to direct said medium towards said carrier wings to assist their action said head flaps being inclined in a direction parallel with said carrier wings. V

5. In a machine for amxing a covering on a bin carrier as an effect of their inclination and.

of the resistance exerted on said wings by the medium through which they travel in the ro tation of said carrier. Y

6. In a machine for aiiixing a covering on a filiform element said covering consisting of a thread wound spirally on said element, an annular rotary head, an annular carrier loosely resting on said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longitudinally through said head, carrier and bobbin,

wings fast on said carrier said Wings developing and applying to said carrier a control action in respect of the rotary movement'thereof as an effect of the resistance exerted on said wings by the medium through which they travel in the rotation of said carrier, and naps on said head said flaps being inclined with respect to the'direction of the respective radius to direct said medium towards said carrier wings to assist their action.

7. In a machine for afiixing a covering on a filiform element said covering consisting of a thread wound spirally on said element, an annular rotary head, an annular carrier loosely resting on said head and frictionally engaged therewith and driven thereby, acovering thread bobbin on said carrier, said element running longi tudinally through said head, carrier and bobbin, wings fast on said carrier said wings being inclinedwith respect to their path line and developing and applying to said carrier an upward thrust to compensate for the weight of said bobbin carrier as an effect of their inclination and of the resistance exerted on said wings by the medium through which they travel in the rota-- tion of said carrier, and flaps on said head to di-' rect said medium towards said carrier wings to assist their action said head flaps being inclined in adirection parallelwith said carrier wings and also inclined with respect to the direction of the respective radius.

8. In a machine for aflixing a covering on a flliform element said covering consisting of a thread wound spirally on said element, an annular rotary head, an annular carrier loosely resting on said head and frictionally engaged therewith and driven thereby, a covering thread bobbin on said carrier, said element running longitudinally through said head, carrier and bobbin,

vmonnzo ANGELO FOLCO. 

